New Pteraspidiform Heterostracans (Vertebrata) from the lower Devonian of La Gileppe and Nonceveux, Belgium

Original material of vertebrates from two Lower Devonian localities of the Belgian Ardenne Massif is described. The material from La Gileppe includes Rhinopteraspis crouchi (Vertebrata, Heterostraci, Pteraspidiformes) and is the first confirmation of vertebrate for this late Lochkovian locality belonging to the Z Spore Zone, and correlated to the lower part of the Althaspis leachi Fish Zone. This confirms the overlapping range of R. crouchi and A. leachi in the siliciclastic Lower Devonian of Western Europe. An orbital plate and two other elements of an undetermined pteraspidiform from Nonceveux are added to the material already known from this locality. The Nonceveux locality is late Lochkovian in age and belongs to the G Spore Zone, which is correlated to the base of the A. leachi Fish Zone. The La Gileppe material is composed of small specimens which are interpreted as either of juvenile individuals or of small adults. It is consistent with previous results on French-Belgian localities among the Early Devonian siliciclastic deposits of Western Europe (Old Red Sandstones and allied facies) which have been interpreted as confined, restricted marine environments

Données nouvelles sur les Hétérostracés (vertébrés, agnathes) du gisement d'Ombret, Dévonien inferieur de l'Ardenne belge

Two heterostracan taxa have been discovered in newly prepared samples of the Gedinnian beds of Ombret (Liège Province, Belgium). These are Pteraspis rostrata (Agassiz) and Poraspis sp. indet. They allow a correlation of the Ombret locality with the Middle Dittonian of Great Britain (Leathensis Zone or the base of the Crouchi Zone) and the Gedinnian of Artois (the highest Lower or basal Upper Gedinnian)

Les heterostracés (vertébrés, agnathes) du Dévonien inférieur du nord de la France et du sud de la Belgique (Artois-Ardenne)

35 localities from the Lower Devonian of Artois-Ardenne have yielded heterostracans or only traces of heterostracans. These localities are reviewed and the revision of the specimens leads to a vertical zonation from the Upper Lower Gedinnian up to the Emsian. The faunal assemblages are then placed in the L. Devonian palaeogeography, along the shore of the Brabant Massif of North-Atlantis

Rise of the Earliest Tetrapods: An Early Devonian Origin from Marine Environment

Tetrapod fossil tracks are known from the Middle Devonian (Eifelian at ca. 397 million years ago - MYA), and their earliest bony remains from the Upper Devonian (Frasnian at 375–385 MYA). Tetrapods are now generally considered to have colonized land during the Carboniferous (i.e., after 359 MYA), which is considered to be one of the major events in the history of life. Our analysis on tetrapod evolution was performed using molecular data consisting of 13 proteins from 17 species and different paleontological data. The analysis on the molecular data was performed with the program TreeSAAP and the results were analyzed to see if they had implications on the paleontological data collected. The results have shown that tetrapods evolved from marine environments during times of higher oxygen levels. The change in environmental conditions played a major role in their evolution. According to our analysis this evolution occurred at about 397–416 MYA during the Early Devonian unlike previously thought. This idea is supported by various environmental factors such as sea levels and oxygen rate, and biotic factors such as biodiversity of arthropods and coral reefs. The molecular data also strongly supports lungfish as tetrapod's closest living relative

The apparatus composition and architecture of Erismodus quadridactylus and the implications for element homology in prioniodinin conodonts

The apparatus composition and architecture of prioniodinin conodonts is poorly understood, largely because few prioniodinin taxa are represented by articulated oral feeding apparatuses (natural assemblages) in the fossil record, but also due to the highly variable gradational morphology of their constituent elements that makes apparatus reconstruction problematic. We describe here a natural assemblage of Erismodus quadridactylus (Stauffer), a prioniodinin, from the Sandbian (Late Ordovician) of North Dakota, USA. The assemblage demonstrates that the apparatus architecture of Erismodus is similar to those of late Palaeozoic prioniodinins namely, Kladognathus Rexroad and Hibbardella Bassler, but also has similarities with ozarkodinin apparatuses. In addition, there is evidence to suggest that E. quadridactylus shares topological similarities to balognathid architecture, with respect to the position of its inferred P elements. The apparatus composition and architecture presented here indicate that, at least with respect to the M–S array, an ‘ozarkodinin‐type’ bauplan is probably more widely representative across prioniodontids. The assemblage demonstrates that element morphotypes traditionally considered to lie within the S array are M elements, whereas others traditionally interpreted as P elements are found in the S array. These observations are used as a basis for refining concepts of element homology among prioniodinin conodonts and their closest relatives

Glass polymorphism in glycerol–water mixtures: I. A computer simulation study

We perform out-of-equilibrium molecular dynamics (MD) simulations of water–glycerol mixtures in the glass state. Specifically, we study the transformations between low-density (LDA) and high-density amorphous (HDA) forms of these mixtures induced by compression/decompression at constant temperature. Our MD simulations reproduce qualitatively the density changes observed in experiments. Specifically, the LDA–HDA transformation becomes (i) smoother and (ii) the hysteresis in a compression/ decompression cycle decreases as T and/or glycerol content increase. This is surprising given the fast compression/decompression rates (relative to experiments) accessible in MD simulations. We study mixtures with glycerol molar concentration wg = 0–13% and find that, for the present mixture models and rates, the LDA–HDA transformation is detectable up to wg E 5%. As the concentration increases, the density of the starting glass (i.e., LDA at approximately wg r 5%) rapidly increases while, instead, the density of HDA remains practically constant. Accordingly, the LDA state and hence glass polymorphism become inaccessible for glassy mixtures with approximately wg 4 5%. We present an analysis of the molecular-level changes underlying the LDA–HDA transformation. As observed in pure glassy water, during the LDA-to- HDA transformation, water molecules within the mixture approach each other, moving from the second to the first hydration shell and filling the first interstitial shell of water molecules. Interestingly, similar changes also occur around glycerol OH groups. It follows that glycerol OH groups contribute to the density increase during the LDA–HDA transformation. An analysis of the hydrogen bond (HB)-network of the mixtures shows that the LDA–HDA transformation is accompanied by minor changes in the number of HBs of water and glycerol. Instead, large changes in glycerol and water coordination numbers occur. We also perform a detailed analysis of the effects that the glycerol force field (FF) has on our results. By comparing MD simulations using two different glycerol models, we find that glycerol conformations indeed depend on the FF employed. Yet, the thermodynamic and microscopic mechanisms accompanying the LDA–HDA transformation and hence, our main results, do not. This work is accompanied by an experimental report where we study the glass polymorphism in glycerol–water mixtures prepared by isobaric cooling at 1 ba

Endoskeletal structure in Cheirolepis (Osteichthyes, Actinopterygii), An early ray-finned fish

As the sister lineage of all other actinopterygians, the Middle to Late Devonian (Eifelian–Frasnian) Cheirolepis occupies a pivotal position in vertebrate phylogeny. Although the dermal skeleton of this taxon has been exhaustively described, very little of its endoskeleton is known, leaving questions of neurocranial and fin evolution in early ray‐finned fishes unresolved. The model for early actinopterygian anatomy has instead been based largely on the Late Devonian (Frasnian) Mimipiscis, preserved in stunning detail from the Gogo Formation of Australia. Here, we present re‐examinations of existing museum specimens through the use of high‐resolution laboratory‐ and synchrotron‐based computed tomography scanning, revealing new details of the neuro‐cranium, hyomandibula and pectoral fin endoskeleton for the Eifelian Cheirolepis trailli. These new data highlight traits considered uncharacteristic of early actinopterygians, including an uninvested dorsal aorta and imperforate propterygium, and corroborate the early divergence of Cheirolepis within actinopterygian phylogeny. These traits represent conspicuous differences between the endoskeletal structure of Cheirolepis and Mimipiscis. Additionally, we describe new aspects of the parasphenoid, vomer and scales, most notably that the scales display peg‐and‐socket articulation and a distinct neck. Collectively, these new data help clarify primitive conditions within ray‐finned fishes, which in turn have important implications for understanding features likely present in the last common ancestor of living osteichthyans

A randomized, double-blind, placebo-controlled trial of coenzyme Q10 in Huntington disease

Objective: To test the hypothesis that chronic treatment of early-stage Huntington disease (HD) with high-dose coenzyme Q10 (CoQ) will slow the progressive functional decline of HD. Methods: We performed a multicenter randomized, double-blind, placebo-controlled trial. Patients with early-stage HD (n = 609) were enrolled at 48 sites in the United States, Canada, and Australia from 2008 to 2012. Patients were randomized to receive either CoQ 2,400 mg/d or matching placebo, then followed for 60 months. The primary outcome variable was the change from baseline to month 60 in Total Functional Capacity score (for patients who survived) combined with time to death (for patients who died) analyzed using a joint-rank analysis approach. Results: An interim analysis for futility revealed a conditional power of <5% for the primary analysis, prompting premature conclusion in July 2014. No statistically significant differences were seen between treatment groups for the primary or secondary outcome measures. CoQ was generally safe and well-tolerated throughout the study. Conclusions: These data do not justify use of CoQ as a treatment to slow functional decline in HD

A critical appraisal of appendage disparity and homology in fishes

Fishes are both extremely diverse and morphologically disparate. Part of this disparity can be observed in the numerous possible fin configurations that may differ in terms of the number of fins as well as fin shapes, sizes and relative positions on the body. Here, we thoroughly review the major patterns of disparity in fin configurations for each major group of fishes and discuss how median and paired fin homologies have been interpreted over time. When taking into account the entire span of fish diversity, including both extant and fossil taxa, the disparity in fin morphologies greatly complicates inferring homologies for individual fins. Given the phylogenetic scope of this review, structural and topological criteria appear to be the most useful indicators of fin identity. We further suggest that it may be advantageous to consider some of these fin homologies as nested within the larger framework of homologous fin‐forming morphogenetic fields. We also discuss scenarios of appendage evolution and suggest that modularity may have played a key role in appendage disparification. Fin modules re‐expressed within the boundaries of fin‐forming fields could explain how some fins may have evolved numerous times independently in separate lineages (e.g., adipose fin), or how new fins may have evolved over time (e.g., anterior and posterior dorsal fins, pectoral and pelvic fins). We favour an evolutionary scenario whereby median appendages appeared from a unique field of competence first positioned throughout the dorsal and ventral midlines, which was then redeployed laterally leading to paired appendages.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151971/1/faf12402_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151971/2/faf12402.pd